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US4176138A
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Process for preparing p-aminophenol in the presence of dimethyldodecylamine sulfate
Assignee: Mallinckrodt Chemical Inc
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Filing: 1978-10-27
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Granted: 1979-11-27
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Expires: 1998-10-27
Abstract
Abstract The preparation of p-aminophenol by the catalytic hydrogenation of nitrobenzene in an acid reaction medium containing an aqueous isopropyl alcohol solution of trimethyldodecylammonium chloride leads to the formation of chloro- and isopropoxyaniline impurities. These end up in the by-product aniline. The substitution of dimethyldodecylamine sulfate for the quaternary salt eliminates these impurities without significant adverse effect on the yield, production rate or purity of the p-aminophenol.
Inventors
- 👤 Sharad S. Sathe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 19:39
CPC Classifications
C; C07; C07C; C07C215/00; C07C215/74; C07C215/76
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
24 words
A method for preparing p-aminophenol, with aniline as a by-product, by the catalytic hydrogenation of nitrobenzene in an acidic reaction medium containing dimethyldodecylamine sulfate.
Claim 2
Independent Claim
24 words
A method for preparing p-aminophenol, with aniline as a by-product, by the catalytic hydrogenation of nitrobenzene in an acidic reaction medium containing dimethyldodecylamine sulfate.
Claim 3
Dependent Claim
15 words
A method as defined by claim 1 wherein the catalyst comprises platinum supported on carbon.
Claim 4
Dependent Claim
16 words
A method as defined by claim 1 wherein the reaction medium is acidified with sulfuric acid.
Claim 5
Dependent Claim
24 words
a method as defined by claim 3 wherein about 0.01% to about 0.2% by volume of dimethyldodecylamine, based on the aqueous medium, is used.
Claim 6
Dependent Claim
18 words
A method as defined by claim 4, wherein the proportion of dimethyldodecylamine is about 0.05% to about 0.15%.
Claim 7
Dependent Claim
35 words
In a method for preparing p-aminophenol, with aniline as a by-product, by the catalytic hydrogenation of nitrobenzene in an acidic reaction medium containing a surfactant, the improvement which comprises using dimethyldodecylamine sulfate as the surfactant.
Claim 8
Dependent Claim
35 words
In a method for preparing p-aminophenol, with aniline as a by-product, by the catalytic hydrogenation of nitrobenzene in an acidic reaction medium containing a surfactant, the improvement which comprises using dimethyldodecylamine sulfate as the surfactant.
References Cited (Backward Citations)
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Cited
US2765342A
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GB856366A
Cited
US3383416A
Cited
US3535382A
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US3654365A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-11-26 | 1983-05-28 | 1983-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-11-26 | 1987-05-28 | 1987-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-11-26 | 1991-05-28 | 1991-11-27 | $7700.00 | Window Closed / Lapsed |